Controlling a viscosity of fuel in a fuel control system with a vibratory meter

ABSTRACT

A method of controlling a viscosity of fuel in a fuel control system with a vibratory meter is provided. The method includes providing the fuel to the vibratory meter, measuring a property of the fuel with the vibratory meter, and generating a signal based on the measured property of the fuel. The method also includes providing the signal to a temperature control unit configured to control the temperature of the fuel provided to the vibratory meter.

TECHNICAL FIELD

The embodiments described below relate to fuel control systems and, moreparticularly, to controlling a viscosity of fuel in a fuel controlsystem with a vibratory meter.

BACKGROUND

Heavy fuel oils (HFOs) are used in the marine industry as fuel forengines. The engine's performance is correlated with how well the fuelinjectors atomize the fuel. The fuel injectors are controlled by acontroller, which is typically an engine control unit (ECU), to ensurethat the atomization is appropriate to achieve the desired performance.For example, the ECU can sense various parameters such as air intakepressure, fuel pressure, and fuel temperature and, from theseparameters, control the fuel injector to increase or decrease the flowrate of the fuel into a combustion chamber.

The fuel properties can determine whether the fuel is appropriate for agiven fuel injector. For example, the fuel at a low temperature may havea viscosity that is too high for the fuel injector. Fuel injectorstypically cannot effectively atomize fuels with high viscosity or canonly atomize fuels within a certain viscosity range. This isparticularly true for HFOs, which have a high viscosity relative toother common fuels, such as gasoline or other distillates.

The marine industry, however, has developed sophisticated engine designsand fuel control systems that are able to utilize the HFOs, as well asother fuels, despite the wide range of viscosities in the fuel supply.These engine designs and fuel control systems employ a variety oftechniques. For example, to reduce the viscosity of the fuel, the enginedesigns may include a heater to heat the fuel. However, the fuel istypically heated at a location that is proximate the fuel source, whichmay be problematic because the fuel control systems typically have longfuel supply lines that cause the fuel to cool before reaching theengine. In addition, the cooling rates along the fuel lines can varysignificantly due to changing environmental conditions around the fuellines. As a result, the viscosity of the fuel as it arrives at theengine may be at a viscosity that is not appropriate for the fuelinjector.

However, the viscosity of the fuel can be controlled if the propertiesof the fuel are measured within a desirable degree of accuracy, whichcan be accomplished with a vibratory meter. Accordingly, there is a needfor controlling a viscosity of fuel in a fuel control system with avibratory meter. There is also a need for controlling the viscosity in amanner that compensates for the heat loss along the fuel lines.

SUMMARY

A method of controlling a viscosity of fuel in a fuel control systemwith a vibratory meter is provided. According to an embodiment, themethod comprises providing the fuel to the vibratory meter, measuring aproperty of the fuel with the vibratory meter, generating a signal basedon the measured property of the fuel, and providing the signal to atemperature control unit configured to control the temperature of thefuel provided to the vibratory meter.

A vibratory meter for controlling a viscosity in a fuel control systemis provided. According to an embodiment, the vibratory meter comprises ameter assembly fluidly coupled to a fuel source and a meter electronicscommunicatively coupled to the meter assembly. The meter electronics isconfigured to measure a property of the fuel with the meter assembly,generate a signal based on the measured property and provide the signalto a temperature control unit configured to control the temperature ofthe fuel provided to the vibratory meter.

A fuel control system configured to control a viscosity of fuel in thefuel control system is provided. According to an embodiment, the fuelcontrol system comprises a vibratory meter fluidly and communicativelycoupled to the temperature control unit and a temperature control unitconfigured to receive fuel from a fuel source and communicatively andfluidly coupled to the vibratory meter. The temperature control unit isconfigured to receive a signal from the vibratory meter and control thetemperature of the fuel based on the signal received from the vibratorymeter.

ASPECTS

According to an aspect, a method of controlling a viscosity of fuel in afuel control system with a vibratory meter comprises providing the fuelto the vibratory meter, measuring a property of the fuel with thevibratory meter, generating a signal based on the measured property ofthe fuel, and providing the signal to a temperature control unitconfigured to control the temperature of the fuel provided to thevibratory meter.

Preferably, the method further comprises providing the signal to a fuelinjection controller configured to control an engine receiving the fuelfrom the vibratory meter. Preferably, the step of generating the signalbased on the measured property of the fuel comprises comparing a valueof the measured property with a reference value and generating a signalin proportion to the difference between the value of the measuredproperty and the reference value.

Preferably, the temperature control unit is comprised of a heaterconfigured to heat the fuel to reduce a viscosity of the fuel.

Preferably, the step of generating the signal based on the measuredproperty of the fuel comprises calculating a viscosity from the measuredproperty of the fuel.

Preferably, the measured property of the fuel is a density of the fuel.

Preferably, the vibratory meter comprises a Coriolis flow meter.

According to an aspect, a vibratory meter (5) for controlling aviscosity in a fuel control system (400) comprises a meter assembly (10)fluidly coupled to a fuel source (410), a meter electronics (20)communicatively coupled to the meter assembly (10), wherein the meterelectronics (20) is configured to measure a property of the fuel withthe meter assembly (10), generate a signal based on the measuredproperty, and provide the signal to a temperature control unit (420)configured to control the temperature of the fuel provided to thevibratory meter (5).

Preferably, the meter electronics (20) is further configured to providethe signal to a fuel injection controller (432) configured to control anengine (439) receiving the fuel from the vibratory meter.

Preferably, the meter electronics (20) being configured to generate thesignal based on the measured property comprises the meter electronics(20) being configured to compare the value of the measured property witha reference value and generate a signal in proportion to the differencebetween the value of the measured property and the reference value.

Preferably, the temperature control unit (420) is comprised of a heater(424) configured to heat the fuel to reduce a viscosity of the fuel.

Preferably, the meter electronics (20) being configured to generate thesignal based on the measured property of the fuel comprises the meterelectronics (20) being configured to calculate a viscosity from themeasured property of the fuel.

Preferably, the measured property comprises a density of the fuel.

Preferably, the vibratory meter comprises a Coriolis flow meter.

According to an aspect, a fuel control system (400) configured tocontrol a viscosity of fuel in the fuel control system (400) comprises avibratory meter (5) fluidly and communicatively coupled to thetemperature control unit (420), a temperature control unit (420)configured to receive fuel from a fuel source (410) and communicativelyand fluidly coupled to the vibratory meter (5) wherein the temperaturecontrol unit (420) is configured to receive a signal from the vibratorymeter (5), and control the temperature of the fuel based on the signalreceived from the vibratory meter (5).

Preferably, the vibratory meter (5) is configured to measure a propertyof the fuel and determine a viscosity of the fuel from the measuredproperty.

Preferably, the vibratory meter (5) is configured to determine areference value and provide the reference value to the temperaturecontrol unit (420) via the signal provided to the temperature controlunit (420).

BRIEF DESCRIPTION OF THE DRAWINGS

The same reference number represents the same element on all drawings.It should be understood that the drawings are not necessarily to scale.

FIG. 1 shows a vibratory meter 5 for controlling a viscosity of fuel ina fuel control system according to an embodiment.

FIG. 2 shows a viscosity-density graph 200 with data illustrating arelationship between a viscosity and a density of the fuel.

FIG. 3 shows a temperature-viscosity graph 300 illustrating arelationship between temperature and viscosity of a fuel.

FIG. 4 shows a fuel control system 400 with the vibratory meter 5 forcontrolling a viscosity of fuel.

FIG. 5 shows a method 500 of controlling a viscosity of fuel in a fuelcontrol system with a vibratory meter according to an embodiment.

DETAILED DESCRIPTION

FIGS. 1-5 and the following description depict specific examples toteach those skilled in the art how to make and use the best mode ofembodiments of controlling a viscosity of fuel in a fuel control systemwith a vibratory meter. For the purpose of teaching inventiveprinciples, some conventional aspects have been simplified or omitted.Those skilled in the art will appreciate variations from these examplesthat fall within the scope of the present description. Those skilled inthe art will appreciate that the features described below can becombined in various ways to form multiple variations of controlling theviscosity of the fuel in a fuel control system with the vibratory meter.As a result, the embodiments described below are not limited to thespecific examples described below, but only by the claims and theirequivalents.

FIG. 1 shows a vibratory meter 5 for controlling a viscosity of fuel ina fuel control system according to an embodiment. As shown in FIG. 1,the vibratory meter 5 comprises a meter assembly 10 and meterelectronics 20. The meter assembly 10 responds to mass flow rate anddensity of a process material. The meter electronics 20 is connected tothe meter assembly 10 via leads 100 to provide density, mass flow rate,and temperature information over path 26, as well as other information.A Coriolis flow meter structure is described although it is apparent tothose skilled in the art that the present invention could be practicedas a vibrating tube densitometer, tuning fork densitometer, or the like.

The meter assembly 10 includes a pair of manifolds 150 and 150′, flanges103 and 103′ having flange necks 110 and 110′, a pair of parallel flowtubes 130 and 130′, drive mechanism 180, resistive temperature detector(RTD) 190, and a pair of pick-off sensors 1701 and 170 r. Flow tubes 130and 130′ have two essentially straight inlet legs 131, 131′ and outletlegs 134, 134′, which converge towards each other at flow tube mountingblocks 120 and 120′. The flow tubes 130, 130′ bend at two symmetricallocations along their length and are essentially parallel throughouttheir length. Brace bars 140 and 140′ serve to define the axis W and W′about which each flow tube 130, 130′ oscillates. The legs 131, 131′ and134, 134′ of the flow tubes 130, 130′ are fixedly attached to flow tubemounting blocks 120 and 120′ and these blocks, in turn, are fixedlyattached to manifolds 150 and 150′. This provides a continuous closedmaterial path through meter assembly 10.

When flanges 103 and 103′, having holes 102 and 102′ are connected, viainlet end 104 and outlet end 104′ into a process line (not shown) whichcarries the process material that is being measured, material entersinlet end 104 of the meter through an orifice 101 in the flange 103 andis conducted through the manifold 150 to the flow tube mounting block120 having a surface 121. Within the manifold 150 the material isdivided and routed through the flow tubes 130, 130′. Upon exiting theflow tubes 130, 130′, the process material is recombined in a singlestream within the block 120′ having a surface 121′ and the manifold 150′and is thereafter routed to outlet end 104′ connected by the flange 103′having holes 102′ to the process line (not shown).

The flow tubes 130, 130′ are selected and appropriately mounted to theflow tube mounting blocks 120, 120′ so as to have substantially the samemass distribution, moments of inertia and Young's modulus about bendingaxes W-W and W′-W′, respectively. These bending axes go through thebrace bars 140, 140′. Inasmuch as the Young's modulus of the flow tubeschange with temperature, and this change affects the calculation of flowand density, RTD 190 is mounted to flow tube 130′ to continuouslymeasure the temperature of the flow tube 130′. The temperature of theflow tube 130′ and hence the voltage appearing across the RTD 190 for agiven current passing therethrough is governed by the temperature of thematerial passing through the flow tube 130′. The temperature dependentvoltage appearing across the RTD 190 is used in a well-known method bythe meter electronics 20 to compensate for the change in elastic modulusof the flow tubes 130, 130′ due to any changes in flow tube temperature.The RTD 190 is connected to the meter electronics 20 by lead 195.

Both of the flow tubes 130, 130′ are driven by drive mechanism 180 inopposite directions about their respective bending axes W and W′ and atwhat is termed the first out-of-phase bending mode of the flow meter.This drive mechanism 180 may comprise any one of many well-knownarrangements, such as a magnet mounted to the flow tube 130′ and anopposing coil mounted to the flow tube 130 and through which analternating current is passed for vibrating both flow tubes 130, 130′. Asuitable drive signal is applied by the meter electronics 20, via lead185, to the drive mechanism 180.

The meter electronics 20 receives the RTD temperature signal on lead195, and the left and right sensor signals appearing on leads 1651, 165r, respectively. The meter electronics 20 produces the drive signalappearing on lead 185 to drive mechanism 180 and vibrate tubes 130,130′. The meter electronics 20 processes the left and right sensorsignals and the RTD signal to compute the mass flow rate and the densityof the material passing through meter assembly 10. This information,along with other information, is applied by meter electronics 20 overpath 26 as a signal.

As will be explained in more detail in the following, the signal can beused to control a viscosity of fuel in a fuel system. For example, thesignal may be used to control a temperature of the fuel in the fuelsystem. By controlling the temperature of the fuel, the fuel provided toan engine may be within a desired range of viscosities. The signal canbe generated based on a property, such as density, measured by thevibratory meter 5, as will be explained in more detail in the following.

FIG. 2 shows a viscosity-density graph 200 with data illustrating arelationship between a viscosity and a density of the fuel. Theviscosity-density graph 200 includes a viscosity axis 210 with alogarithmic scale that ranges from 1.00 E-02 to 1.00 E-03 centistokes(cSt). The viscosity-density graph 200 also includes a density axis 220that ranges from 600.00 to 1,100.00 kg/m³. Although theviscosity-density relationship of the fuel is respectively expressed inunits of centistokes and kg/m³, other units may be employed inalternative embodiments.

The viscosity-density graph 200 shows a line 240 that is a linear fit toviscosity-density data points 250 depicted as circles. The line 240 canbe calculated from the viscosity-density data points 250 using anyappropriate method, such as, for example, linear regression. The line240 may be stored as a data set, equation, or the like, in the meterelectronics 20. The viscosity-density data points 250 can be determinedthrough various means including, for example, measuring the viscosityand density of various fuel types over a range of temperatures.

As can be appreciated from FIG. 2, the line 240 is a close approximationof the viscosity-density data points 250. In other words, theviscosity-density data points 250 are relatively close to the line 240along the entire length of the line. Accordingly, the line 240 may beused to provide a relationship, within a range of accuracy, between thedensity and the viscosity of the fuel. The viscosity of the fuel can bedetermined from the density of the fuel using the viscosity-densityrelationship. For example, the vibratory meter 5 can measure the densityof the fuel in the vibratory meter 5. Using the measured density of thefuel, the line 240 can be used to determine a corresponding viscosity ofthe fuel. Other fuel properties, such as temperature, may be correlatedwith the viscosity of the fuel.

FIG. 3 shows a temperature-viscosity graph 300 illustrating arelationship between a temperature and a viscosity of a fuel. Thetemperature-viscosity graph 300 includes a temperature axis 310 and aviscosity axis 320. The temperature axis 310 is in units of degreesCelsius (° C.) and the viscosity axis 320 is in units of centistokes(cSt). The viscosity axis 320 is shown with a logarithmic scale. Inalternative embodiments, any suitable units and scales may be employed.

The temperature-viscosity graph 300 also includes temperature-viscosityplots 330 that trend down as the temperature increases. Thetemperature-viscosity plots 330 include a high viscosity fuel plot 332,a moderate viscosity fuel plot 334, and a low viscosity fuel plot 336.Each of the temperature-viscosity plots 330 may represent a particulargrade of fuel, where the fuel grades have different viscosities. Thetemperature-viscosity plots 330 may be obtained in any appropriatemanner such as, for example, querying empirical data of the fuelsupplied to a tank, referencing a table with viscosity-fuel grade data,or the like. The temperature-viscosity graph 300 also illustrates a lowtemperature viscosity region 330 a and an operating viscosity region 330b.

The low temperature viscosity region 330 a may be the viscosity of thefuel when the fuel is not heated. For example, the low temperatureviscosity region 330 a may be representative of the fuel when the fuelis in the tank. As can be appreciated from FIG. 3, the low temperatureviscosity region 330 a has a relatively wide range of viscosities forthe temperature-viscosity plots 330 at a given temperature. For example,at 40 degrees Celsius, the high viscosity fuel plot 332 has a viscosityof 2000 centistokes. The low viscosity fuel plot 336 has a viscosity ofabout 700 centistokes at 40 degrees Celsius. The difference between thehigh viscosity fuel plot 332 and the low viscosity fuel plot 336, at 40degrees Celsius, is therefore about 1300 centistokes.

In contrast, the operating viscosity region 330 b has a more narrowrange of viscosities. For example, at 140 degrees Celsius, the highviscosity fuel plot 332 has a viscosity of 20 centistokes. The viscosityof the low viscosity fuel plot 336 at 140 degrees Celsius is about 15centistokes. Accordingly, rather than the 1300 centistokes difference at40 degrees Celsius, the difference between the high and low viscosityfuel plots 332, 336 at 140 degrees is about 5 centistokes. Accordingly,the different fuel grades in the operating viscosity region 330 b mayhave a property, such as viscosity, that is appropriate for a fuelinjector in a fuel control system, which is described in more detail inthe following.

FIG. 4 shows a fuel control system 400 with the vibratory meter 5 forcontrolling a viscosity of fuel. The fuel control system 400 includes afuel source 410 that is in fluid communication with a temperaturecontrol unit 420, the vibratory meter 5 described with reference to FIG.1, and a fuel injection system 430. The temperature control unit 420 isfluidly coupled with the vibratory meter 5 via the fuel line 425. Thelength of the fuel line 425 is illustrated by broken lines. Thetemperature control unit 420 is also communicatively coupled to thevibratory meter 5 via the communications path 429, which may be aportion of the path 26 described in the foregoing with reference to FIG.1.

In the embodiment of FIG. 4, the fuel source 410 includes a fuel port412 and a tank 414. Shown proximate the fuel port 412 is an arrow thatillustrates fuel being supplied to the fuel port 412. The tank 414 isfluidly coupled to the fuel port 412 and configured to receive the fuelsupplied to the fuel port 412. The tank 414 is shown as partially filledwith fuel (an exemplary fuel level being illustrated by the wavy line).Near the bottom of the tank 414 is a fuel line that fluidly couples thetank 414 to the temperature control unit 420.

The temperature control unit 420 includes a temperature controller 422that is electrically coupled to a heater 424 configured to heat the fuelas it flows through the heater 424. The temperature controller 422 isalso communicatively coupled to a viscometer 426, a temperaturetransducer 428, and the meter electronics 20 in the vibratory meter 5.As can be appreciated from FIG. 4, the fuel can flow from the tank 414to the fuel line 425 through the heater 424 and the viscometer 426. Thetemperature transducer 428 can measure the temperature of the fuel andprovide a signal to the temperature controller 422.

The temperature controller 422 can be configured to provide power, suchas, for example, electrical power to the heater 424. The power providedto the heater 424 may be proportional to the heat that is transferredfrom the heater 424 to the fuel flowing through the heater 424. Thepower provided to the heater 424 may be proportional to a differencebetween the temperature measured by the temperature transducer 428 and atemperature reference.

The temperature controller 422 can also receive a signal withinformation about the fuel flowing through the viscometer 426. Forexample, the temperature controller 422 can receive a voltage signalfrom the viscometer 426 that is proportional to the viscosity of thefuel. Alternatively, the viscometer 426 may provide a digital value thatrepresents the viscosity of the fuel. Other means of providing theinformation to the temperature controller 422 may be employed inalternative embodiments. Similarly, the temperature controller 422 canreceive a signal from the temperature transducer 428 that includesinformation about the temperature of the fuel flowing through the fuelline 425. The measured temperature may be the temperature of the fuel,the fuel line, surrounding air, etc.

Although the foregoing describes an embodiment of the temperaturecontrol unit 420 that includes the temperature controller 422, theheater 424, the viscometer 426, and the temperature transducer 428,alternative embodiments may have different configurations. For example,embodiments may not include the viscometer 426 and, instead, may rely onthe vibratory meter 5 to determine the viscosity of the fuel. However,the viscometer 426 may be advantageous because it can measure theviscosity of the fuel as the fuel exits the heater 424 and provideinformation about the viscosity to the temperature controller 422 and/orthe meter electronics 20, which can compare the viscosity withmeasurements made by the meter assembly 10. It can also be appreciatedthat the temperature controller 422 may not be part of the temperaturecontrol unit 420. For example, the temperature control unit 420 could bepart of the meter electronics 20 in the vibratory meter 5 described inthe foregoing with reference to FIG. 1.

In FIG. 4, the vibratory meter 5 is shown with the meter electronics 20in communication with the meter assembly 10. The meter electronics 20 isalso shown to be communicatively coupled to the temperature control unit420 and the fuel injection system 430. The meter electronics 20 may beconfigured to provide a signal to the temperature control unit 420and/or the fuel injection system 430. For example, the meter electronics20 may receive a measurement, such a density of the fuel in the meterassembly 10, and calculate a reference value that can be sent to thetemperature control unit 420 and/or the fuel injection system 430.

The fuel injection system 430 is shown as including a fuel injectioncontroller 432 that is communicatively coupled to the meter electronics20. The fuel injection controller 432 is also communicatively coupled toa fuel pump 434 and fuel injectors 438. The fuel pump 434 is fluidlycoupled to the fuel injectors 438 via a fuel distributor 436. The fuelpump 434 is configured to supply fuel at a pressure to the fuelinjectors 438 through the fuel distributor 436. The fuel injectors 438inject fuel into an engine 439.

The fuel injection controller 432 is configured to control theparameters of the fuel injection system 430. For example, the fuelinjection controller 432 can regulate the pressure of the fuel exitingthe fuel pump 434. Accordingly, the pressure at the fuel injectors 438can be a desired value. Other parameters, such as operating parametersof the fuel injectors 438, may also be controlled.

In the embodiment shown in FIG. 4, the fuel injection controller 432 cancontrol the parameters of the fuel injection system 430 based on thesignal received from the meter electronics 20. For example, the meterelectronics 20 could generate and provide a signal with informationabout the fuel flowing through the meter assembly 10. The informationcan include, for example, density, viscosity, and temperature of thefuel. Using the information, the fuel injection controller 432 maydetermine the desired operating parameters of the fuel injection system430. For example, the fuel injection controller 432 may adjust the fuelpressure leaving the fuel pump 434 based on the viscosity of the fuel.

In alternative embodiments, the fuel injection system 430 may not be incommunication with the meter electronics 20. Accordingly, the fuelinjection system 430 may not receive information about the viscosity ortemperature of the fuel. In the foregoing described and otherembodiments, the fuel control system 400 may control the viscosity ofthe fuel, as will be described in more detail in the following.

FIG. 5 shows a method 500 for controlling a viscosity of fuel in a fuelcontrol system with a vibratory meter according to an embodiment. Themethod 500 begins with step 510 by providing fuel to a vibratory meter.For example, referring to the fuel control system 400 described in theforegoing, the method 500 can provide fuel from the fuel source 410 tothe vibratory meter 5 via the temperature control unit 420. In step 520,a property of the fuel is measured by the vibratory meter. The propertyof the fuel may include a density, temperature, or the like. In step530, the method 500 may generate a signal based on the measured propertyof the fuel. For example, the generated signal may be based on aviscosity calculated from a density measurement using a relationshipbetween fuel properties. In step 540, the method 500 provides thegenerated signal to a temperature control unit, such as the temperaturecontrol unit 420 described in the foregoing with reference to FIG. 4.

For example, with reference to the embodiment shown in FIG. 2, the line240 may be employed to determine a viscosity from a measured density.The meter electronics 20 can receive the measured density of the fuelvia the leads 100 described with reference to FIG. 1. The measureddensity can be used as a dependent variable in calculating acorresponding determined viscosity. The measured density may be employedas it is received by the meter electronics 20 or stored in the meterelectronics 20 for later use. Using the measured density and the line240 described in the foregoing, the viscosity of the fuel in the meterassembly 10 can be determined. The determined viscosity may then be usedto calculate a reference value.

The reference value compensates for the distance between the temperaturecontrol unit 420 and the vibratory meter 5. As discussed in theforegoing, the distance between the temperature control unit 420 and thevibratory meter 5 is illustrated in FIG. 4 as broken lines in the fuelline 425. Due to this distance, the fuel will cool after being heated bythe heater 424. The reference value may therefore compensate for thecooling of the fuel as it flows through the fuel line 425. Otherfactors, such as, for example, a mass flow rate of the fuel through thefuel line 425 may also be compensated.

The reference value may be provided to the temperature control unit 420by the meter electronics 20 via a generated signal. For example, themeter electronics 20 can generate a digital representation of thereference value and modulate a signal with the digital representation.Accordingly, the generated signal provided by the meter electronics 20may be the signal modulated by the digital representation of thereference value. Other methods may be employed, such as, for example, ananalog direct current (DC) voltage that is proportional to the referencevalue. In an embodiment, the signal may be proportional to thedifference between a measured value and the reference value.

The reference value provided by the meter electronics 20 may be anyappropriate value that can be employed to control the viscosity of thefuel. For example, the reference value provided to the temperaturecontrol unit 420 may be a reference viscosity. That is, the meterelectronics 20 can determine the viscosity from the measured density ofthe fuel in the meter assembly 10 and calculate the reference viscosityusing one of the temperature-viscosity plots 330 by employing a measuredtemperature provided by the temperature control unit 420. Thetemperature control unit 420 can calculate the reference temperaturefrom the reference viscosity using, for example, one of thetemperature-viscosity plots 330 shown in FIG. 3.

In an alternative embodiment, the reference value provided by the meterelectronics 20 may be the reference temperature. In this embodiment, themeter electronics 20 may provide the reference temperature to thetemperature control unit 420. The temperature control unit 420 mayreceive the reference temperature and heat the fuel to the referencetemperature with the heater 424. Additionally or alternatively, themeter electronics 20 may provide other reference values.

Using the reference temperature, the temperature control unit 420 canemploy any suitable control means, such as, for example,proportional-integral-differential (PID) control algorithms. Forexample, the control means may compare the reference temperature that isprovided by the meter electronics 20 or determined by the temperaturecontrol unit 420 with the temperature measured by the temperaturetransducer 428 and adjust the amount of power provided to the heater 424based on the comparison. The amount of power provided may beproportional to the difference between the reference temperature and themeasured temperature.

Due to the vibratory meter 5 being in the fuel control system 400 at adifferent location than the temperature control unit 420, the referencetemperature provided to the temperature control unit 420 may not be thesame as a desired temperature for the fuel flowing through the meterassembly 10. The difference can be proportional to the distance betweenthe temperature control unit 420 and the vibratory meter 5. The distancebetween the temperature control unit 420 and the vibratory meter 5 maybe, for example, 100 meters, although any distance may be present inalternative embodiments. Accordingly, the reference temperature can behigher than the desired fuel temperature at the vibratory meter 5.

The embodiments described above control a viscosity of fuel in a fuelcontrol system 400 with a vibratory meter 5. As explained in theforegoing, the viscosity of the fuel in the fuel control system 400 maybe controlled by controlling the temperature of the fuel. Thetemperature may be controlled by a temperature control unit 420 with,for example, the heater 424. The heater 424 may heat the fuel to areference temperature. Therefore, the fuel entering the fuel injectionsystem 430 may have appropriate fuel properties. For example, theviscosity of the fuel in the fuel injection system 430 may be within theoperating viscosity region 330 b shown in FIG. 3.

In some embodiments, the determined viscosity can be provided to a fuelinjection system 430. For example, the fuel injection controller 432 cancontrol various parameters in the fuel injection system 430 using thedetermined viscosity. Therefore, the fuel pump 434 and the fuelinjectors 438 can be controlled in a manner appropriate for the fuelthat is being received by the fuel injection system 430. For example,the fuel pressure of the fuel exiting the fuel pump 434 may beappropriate for the viscosity determined by the vibratory meter 5.

The detailed descriptions of the above embodiments are not exhaustivedescriptions of all embodiments contemplated by the inventors to bewithin the scope of the present description. Indeed, persons skilled inthe art will recognize that certain elements of the above-describedembodiments may variously be combined or eliminated to create furtherembodiments, and such further embodiments fall within the scope andteachings of the present description. It will also be apparent to thoseof ordinary skill in the art that the above-described embodiments may becombined in whole or in part to create additional embodiments within thescope and teachings of the present description.

Thus, although specific embodiments are described herein forillustrative purposes, various equivalent modifications are possiblewithin the scope of the present description, as those skilled in therelevant art will recognize. The teachings provided herein can beapplied to other vibratory meters that control a viscosity of fuel in afuel control system and not just to the embodiments described above andshown in the accompanying figures. Accordingly, the scope of theembodiments described above should be determined from the followingclaims.

1. A method of controlling a viscosity of fuel in a fuel control systemwith a vibratory meter, the method comprised of: providing the fuel tothe vibratory meter; measuring a property of the fuel with the vibratorymeter; generating a signal based on the measured property of the fuel;and providing the signal to a temperature control unit configured tocontrol the temperature of the fuel provided to the vibratory meter. 2.The method of claim 1, further comprising providing the signal to a fuelinjection controller configured to control an engine receiving the fuelfrom the vibratory meter.
 3. The method of claim 1, wherein the step ofgenerating the signal based on the measured property of the fuelcomprises: comparing a value of the measured property with a referencevalue; and generating a signal in proportion to the difference betweenthe value of the measured property and the reference value.
 4. Themethod of claim 1, wherein the temperature control unit is comprised ofa heater configured to heat the fuel to reduce a viscosity of the fuel.5. The method of claim 1, wherein the step of generating the signalbased on the measured property of the fuel comprises calculating aviscosity from the measured property of the fuel.
 6. The method of claim1, wherein the measured property of the fuel is a density of the fuel.7. The method of claim 1, wherein the vibratory meter comprises aCoriolis flow meter.
 8. A vibratory meter (5) for controlling aviscosity in a fuel control system (400), the vibratory meter (5)comprising: a meter assembly (10) fluidly coupled to a fuel source(410); a meter electronics (20) communicatively coupled to the meterassembly (10), wherein the meter electronics (20) is configured to:measure a property of the fuel with the meter assembly (10); generate asignal based on the measured property; and provide the signal to atemperature control unit (420) configured to control the temperature ofthe fuel provided to the vibratory meter (5).
 9. The vibratory meter (5)of claim 8, wherein the meter electronics (20) is further configured toprovide the signal to a fuel injection controller (432) configured tocontrol an engine (439) receiving the fuel from the vibratory meter (5).10. The vibratory meter (5) of claim 8, wherein the meter electronics(20) being configured to generate the signal based on the measuredproperty comprises the meter electronics (20) being configured to:compare the value of the measured property with a reference value; andgenerate a signal in proportion to the difference between the value ofthe measured property and the reference value.
 11. The vibratory meter(5) of claim 8, wherein the temperature control unit (420) is comprisedof a heater (424) configured to heat the fuel to reduce a viscosity ofthe fuel.
 12. The vibratory meter (5) of claim 8, wherein the meterelectronics (20) being configured to generate the signal based on themeasured property of the fuel comprises the meter electronics (20) beingconfigured to calculate a viscosity from the measured property of thefuel.
 13. The vibratory meter (5) of claim 8, wherein the measuredproperty comprises a density of the fuel.
 14. The vibratory meter (5) ofclaim 8, wherein the vibratory meter (5) comprises a Coriolis flowmeter.
 15. A fuel control system (400) configured to control a viscosityof fuel in the fuel control system (400), comprising: a vibratory meter(5) fluidly and communicatively coupled to the temperature control unit(420); and a temperature control unit (420) configured to receive fuelfrom a fuel source (410) and communicatively and fluidly coupled to thevibratory meter (5) wherein the temperature control unit (420) isconfigured to: receive a signal from the vibratory meter (5); andcontrol the temperature of the fuel based on the signal received fromthe vibratory meter (5).
 16. The fuel control system (400) of claim 15,wherein the vibratory meter (5) is configured to: measure a property ofthe fuel; and determine a viscosity of the fuel from the measuredproperty.
 17. The fuel control system (400) of claim 15, wherein thevibratory meter (5) is configured to determine a reference value andprovide the reference value to the temperature control unit (420) viathe signal provided to the temperature control unit (420).